Process for solidifying organic and inorganic provisional constituents contained in produced water from heavy oil operations

Abstract

A process is provided for treating produced water recovered from an oil recovery process. An oil-water mixture is collected from an oil bearing formation. The oil-water mixture is directed to a separator that separates the oil-water mixture to yield produced water and an oil product. The produced water includes water, dissolved organics and dissolved inorganic solids. The produced water is directed to a crystallizer. In the crystallizer, the produced water is concentrated by heating the produced water. Concentrating the produced water causes the organic and inorganic solids to precipitate from the produced water and form solid crystals, including salt crystals. Further, concentrating the produced water in the crystallizer produces an organic melt including the solid crystals. Thereafter, the method or process entails cooling the organic melt such that the organic melt solidifies into an organic solid structure, and wherein substantially no free water is present in the organic solid structure.

The invention claimed is: 
     
       1. A method for treating produced water recovered from a oil recovery process comprising:
 collecting an oil-water mixture from an oil bearing formation; 
 separating oil from the oil-water mixture to yield produced water comprising water, organics, and dissolved solids; 
 directing the produced water into a crystallizer; 
 concentrating the produced water by heating the produced water in the crystallizer and removing water from the produced water and producing a vapor and an organic melt containing solid crystals; and 
 cooling the organic melt such that the organic melt solidifies into an organic solid structure containing the solid crystals, and wherein substantially no free water is present in the organic solid structure. 
 
     
     
       2. The method of  claim 1  wherein concentrating the produced water comprises concentrating the produced water to a total solids concentration of 75% to 85% by weight. 
     
     
       3. The method of  claim 2  wherein heating the produced water comprises heating the produced water to a temperature of approximately 100° C. to approximately 120° C. 
     
     
       4. The method of  claim 3  wherein cooling the organic melt comprises cooling the organic melt to a temperature of approximately 20° C. to approximately 30° C. 
     
     
       5. The method of  claim 1  wherein after cooling, the organic solid structure has a compressive strength of approximately 3,500 kg/m 2  or higher. 
     
     
       6. The method of  claim 1  further comprising blending fly ash into the organic melt prior to forming the organic solid structure. 
     
     
       7. The method of  claim 6  wherein blinding fly ash comprises adding fly ash to the organic melt at a ratio of approximately 1 to 2 or 1 to 1. 
     
     
       8. The method of  claim 1  wherein the produced water includes a relatively high concentration of sodium chloride relative to the concentration of non-sodium chloride inorganic solids in the produced water, and wherein concentrating the produced water causes the sodium chloride to precipitate from the produced water and form sodium chloride crystals; and wherein after cooling the organic melt, the sodium chloride crystals are contained in the organic solid structure. 
     
     
       9. The method of  claim 1  further comprising adding calcium chloride to the organic melt prior to forming the organic solid structure. 
     
     
       10. The method of  claim 9  wherein adding calcium chloride comprises adding between 0.5% to 4.0% by weight calcium chloride to the organic melt. 
     
     
       11. The method of  claim 1  further comprising coating the organic solid structure. 
     
     
       12. A method of recovering oil from an oil well and treating produced water, comprising:
 (a) recovering an oil-water mixture from the oil well; 
 (b) separating the oil-water mixture to produce an oil product and the produced water that includes dissolved inorganic and organic solids; 
 (c) concentrating the produced water in an evaporator to produce a distillate and evaporator blowdown wherein the evaporator blowdown includes dissolved inorganic and organic solids; 
 (d) directing the distillate to a steam generator and producing steam; 
 (e) injecting the steam into an injection well which gives rise to the oil-water mixture in the oil well; and 
 (f) directing the evaporator blowdown to a crystallizer and
 (i) concentrating the evaporator blowdown in the crystallizer by heating the evaporator blowdown; 
 (ii) wherein concentrating the evaporator blowdown forms an organic melt and causes dissolved solids in the evaporator blowdown to precipitate and crystallize to form solid crystals which are suspended in the organic melt; and 
 (iii) solidifying the organic melt by cooling the organic melt resulting in a solidified organic melt having solid crystals suspend therein. 
 
 
     
     
       13. The method of  claim 12  wherein the solidified organic melt is suitable for disposal in a landfill. 
     
     
       14. The method of  claim 12  including concentrating the evaporator blowdown to where the concentrated evaporator blowdown includes a solids concentration of approximately 75% to approximately 85% by weight. 
     
     
       15. The method of  claim 12  including heating the evaporator blowdown to a temperature of approximately 100° C. to approximately 120° C. 
     
     
       16. The method of  claim 12  further including blending fly ash into the organic melt prior to cooling the organic melt. 
     
     
       17. The method of  claim 12  further comprising adding calcium chloride to the organic melt prior to cooling the organic melt. 
     
     
       18. The method of  claim 12  further including coating the solidified organic melt. 
     
     
       19. The method of  claim 12  including removing substantially all free water from the evaporator blowdown in the crystallizer. 
     
     
       20. The method of  claim 12  further including:
 (a) concentrating the evaporator blowdown to where the concentrated evaporator blowdown includes a solids concentration of approximately 75% approximately 85% by weight; and 
 (b) concentrating the evaporator blowdown such that substantially all free water from the evaporator blowdown is removed. 
 
     
     
       21. The method of  claim 20  further including heating the evaporator blowdown to a temperature of approximately 100° C. to approximately 120° C. 
     
     
       22. The method of  claim 21  further including blending fly ash into the organic melt prior to cooling the organic melt or adding calcium chloride to the organic melt prior to cooling the organic melt. 
     
     
       23. The method of  claim 8  wherein the sodium chloride crystals constitute approximately 14% to approximately 16% of the organic solid structure.